1. Field of the Invention
The present invention generally relates to an electronic endoscope comprising a flexible conduit or scope and a video-signal processing unit to which the flexible scope is detachably connected at a proximal end thereof, and more particularly relates to a connection system for establishing a connection between the flexible scope and the video-signal processing unit.
2. Description of the Related Art
In such an electronic endoscope, the flexible scope includes an objective lens system provided at the distal end thereof, and a solid-state image sensor, such as a CCD (charge-coupled-device) image sensor, associated therewith. The flexible scope also includes an optical light guide extended therethrough, formed as a bundle of optical fibers, which is associated with a lighting lens system provided at the distal end of the flexible scope.
On the other hand, the video-signal processing unit includes a white-light source, such as a halogen lamp, a xenon lamp or the like. When the flexible scope is connected to the video-signal processing unit, the proximal end of the optical light guide is optically connected to the light source. Thus, an object to be photographed is illuminated by light radiating from the distal end of the optical light guide, and is focused as an optical image on a light-receiving surface of the CCD image sensor by the objective lens system.
The focused optical image is converted into a frame of analog image-pixel signals by the CCD image sensor. Then, the frame of analog image-pixel signals is read from the CCD image sensor by a CCD driver circuit provided in the flexible scope, and is fed to the video-signal processing unit, in which the image-pixel signals are suitably processed, thereby producing a video signal including image-pixel signals and various synchronizing signals. Then, the video signal is fed from the video-signal processing unit to a TV monitor to reproduce the photographed object on the monitor in accordance with the video signal.
The connection between the flexible scope and the video-signal processing unit is performed by the connection system including a connector, which comprises a set of connector halves. One of the connector halves is provided at the proximal end of the flexible scope, and the other connector half is provided in a housing wall of the video-signal processing unit. The connector half of the flexible scope has a plurality of contact pins which are electrically connected to various electric lines, such as an electric power line, a ground line, control-signal lines, image-signal lines and so on, extending to the CCD driver circuit and the image sensor, and the connector half of the video-signal processing unit also has a plurality of sheath-like contacts which are electrically connected to various electric lines, such as an electric power line, a ground line, control-signal lines, image-signal lines and so on, extending to a control circuit board of the video-signal processing unit. Namely, the CCD image sensor and the CCD driver circuit are electrically connected to the control circuit board of the video-signal processing unit via the connection between the connector halves.
In the conventional connection system, a user is obligated to turn OFF a power ON/OFF switch of the video-signal precessing unit when connecting the connector halves to each other, because undesirable and imprudent electric currents are produced between the power lines and the signal lines when a connection is established between the ground lines late after an establishment of a connection between the power lines and an establishment of connections between the signal lines. Nevertheless, the connection of the connector halves may be frequently carried out by the user while the power ON/OFF switch is turned ON.
Also, in the conventional connection system, when a contact pin and a sheath-like contact, exhibiting differing electrostatic potentials, are connected to each other, the electrostatic potential difference therebetween produces an electric current. Thus, conventionally, a by-pass diode is provided in each of the signal lines as a static-electricity-protector, to thereby eliminate a produced electric current from a signal line concerned via the by-pass diode. However, the by-pass diode is relatively costly as an electronic element, and thus the conventional connection system is expensive.
Therefore, an object of the present invention is to provide a connection system for establishing a connection between a flexible scope and a video-signal processing unit, wherein the establishment of the connection between the flexible scope and the video-signal processing unit can be properly performed under the condition in which an power ON/OFF switch of the video-processing unit is turned ON.
Another object of the present invention is to provide a connection system as mentioned above, which is arranged such that a low-cost static-electricity-protector can be provided in each of signal lines of the connection system.
In accordance with an aspect of the present invention, there is provided a connection system for establishing a detachable connection between a scope and a video-signal processing unit which form an electronic endoscope. The scope has a solid-state image sensor to produce image-pixel signals, and the video-signal processing unit has a processor for processing the image-pixel signals to produce a video signal. The scope includes a first power line, a first group of signal lines and a first ground line which are utilized to feed the image-pixel signals to the video-signal processing unit, and the video-signal processing unit includes a second power line, a second group of signal lines and a second ground line which are utilized to receive the image-pixel signals from the scope. The connection system comprises a connector that includes a first connector half provided on the scope, and a second connector half provided on the video-signal processing unit. The first power line, first group of signal lines and first ground line are connected to the second power line, second group of signal lines and second ground line, respectively, by establishing a connection between the first and second connector halves. The connection system also comprises a power switch element provided in one of the first and second power lines, and a power controller that changes an OFF-state of the power switch element to an ON-state after the respective connections are completely established between the first power line, first group of signal lines and first ground line and the second power line, second group of signal lines and second ground line.
Preferably, the power controller comprises a first power control line included in the scope, and a second power control line included in the video-signal processing unit. In this case, a connection between the first and second power control lines is established after the respective connections are completely established between the first power line, first group of signal lines and first ground line and the second power line, second group of signal lines and second ground line, and the change of the OFF-state of the power switch element to the ON-state is performed by the power controller when the connection is established between the first and second power control lines.
The power switch element may comprise a transistor which is arranged so as to be turned ON by the establishment of the connection between the first and second power control lines.
When the power switch element is provided in the second power line, the connection system may further comprise a switch circuit that controls an output of the video signal from the video-signal processing unit. In this case, an OFF-state of the switch circuit is changed to an ON-state when the change of the OFF-state of the power switch element to the ON-state is performed by the power controller, whereby the output of the video signal from the video-signal processing unit is enabled.
Furthermore, the connection system may comprise a monitor that reproduces an image on the basis of the output of the video signal from the video-signal processing unit, and a character-display-controller that displays a message on the monitor announcing the establishment of the complete connections between the first power line, first group of signal lines and first ground line and the second power line, second group of signal lines and second ground line when the change of the OFF-state of the power switch element to the ON-state is performed by the power controller.
Also, the connection system may further comprise an indicator that indicates the establishment of the complete connections between the first power line, first group of signal lines and first ground line and the second power line, second group of signal lines and second ground line when the change of the OFF-state of the power switch element to the ON-state is performed by the power controller. Preferably, the indicator comprises a light-emitting diode which is arranged so as to be lit when the change of the OFF-state of the power switch element to the ON-state is performed by the power controller.
Preferably, a transistor is provided in each of the signal lines included in the second group, and the transistor usually is in an ON-state such that the corresponding signal line is grounded, whereby the transistor serves as a static-electricity-protector for the corresponding signal. The ON-state of the transistor is changed to an OFF-state when the change of the OFF-state of the power switch element to the ON-state is performed by the power controller. In this case, a by-pass diode, which serves as a static-electricity-protector, may be provided in the second power control line.
In accordance with another aspect of the present invention, there is provided a connector which comprises a first connector half having a plurality of male contacts, and a second connector half having a plurality of female contacts. The respective male contacts are electrically connected to the female contacts when establishing a connection between the first and second connector halves, and one of the male contacts and a corresponding one of the female contacts are arranged so as to be electrically contacted to each other late after the respective connections are completely established between the remaining male contacts and the remaining female contacts.
Each of the male contacts may be formed as a contact pin, and each of the female contacts may be formed as a sheath-like contact. Also, the aforementioned one of the male contacts may be formed as a shorter pin than the remaining contact pins, and the aforementioned corresponding one of the female contacts is formed as a shorter sheath-like contact than the remaining sheath-like contacts.